The overall program will use a combination of structural, chemical, and biological tools to further anti-AIDS drug and vaccine development. Structure-based methods have accelerated the successful development of several classes of anti-AIDS drugs. We will apply structure-based design methods to develop novel anti- AIDS drugs targeting RNase H (Projects 1-4) and (Projects 1,2, and 4) activities. We also seek to establish some of the basic principles required for using structural information to guide the design of more potent viral and synthetic immunogens as potential AIDS vaccines. Project 1 (Edward Arnold; CABM, Rutgers) will use X-ray crystallography to determine structures of wild-type and drug-resistant HIV-1 RT in complex with inhibitors that target multiple sites on the enzyme. Project 2 (Stephen Hughes; NIH NCI-Frederick) will engineer and produce the HIV RT constructs on a large scale for structural (Project 1) and biochemical/mechanistic studies (Projects 2 and 3), including wild-type and mutant HIV-1 RT, and Cys containing RT mutants engineered for mechanistic and structural studies. Project 3 (Michael Parniak, Pittsburgh) will pursue structure-based design of RNase H inhibitors (with Project 1), including chemical synthesis, mechanistic and resistance studies. Project 4 (Roger Jones; Rutgers) will synthesize oligonucleotides that are tailored for structural and mechanistic studies (with Projects 2, 3, and 4) and dinucleoside tetraphosphates as potential RT inhibitors.